Wave energy transformer

ABSTRACT

An installation for extracting energy from a liquid in which swell occurs relative to a bottom. The installation includes a first and second container for placing at a determined horizontal first mutual distance at least partially under the surface of the liquid, each provided with a closed upper side directed toward the liquid surface, closed side walls and an open underside directed toward the bottom for enclosing a gas under the liquid surface. The gas is bounded to the underside of the container by a quantity of liquid entering via this underside, which quantity of liquid varies as a result of the swell. A transport conduit is provided for transporting gas from the first to the second container and vice versa. A generator responding to the variation in the quantity of liquid in at least one of the containers for generating energy from this variation is also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an installation for extracting energy from aliquid in which swell occurs relative to a bottom.

Such an installation is particularly suitable for use in extractingenergy from waves of water at sea.

2. Description of the Prior Art

It is known of waves at sea that they can occur in a wide range ofamplitudes and frequencies. Extracting energy from swelling sea-water isof particular interest when the waves occurring in the-swelling waterhave been subjected to wind over very great distances (from hundreds tothousands of kilometers). Such waves may be present practicallycontinuously at determined locations along a sea or ocean coast, whereinthe wave length may amount to for instance 60 to 120 meters and theamplitude to for instance 1-3 meters.

It is generally known that variations in the pressure of swelling waterdecrease from the liquid surface in downward direction such that, at adepth corresponding with roughly half the wave length of the occurringwaves, pressure variations are practically no longer detectable. Thismeans that waves with a relatively small wave length have littleinfluence on the dynamic hydrostatic pressure of the underlying watermass. Waves occurring during gales with a wave length of about 30 meterswill for instance not penetrate to a depth further than about 15 meters.Pressure variations caused by a swelling water mass, wherein the wavelength of the occurring waves amounts to for example about 130 meterswill however be felt to a depth of about 65 meters.

It is an object of the invention to provide an installation of the typestated in the preamble, wherein the installation has a high performance,can extract energy from a swelling liquid with large wave lengths andcan be placed on for instance the sea-bed.

SUMMARY OF THE INVENTION

The object of the invention is achieved with an installation of the typestated in the preamble of claim 1, comprising

a first and second container for placing at a determined horizontalfirst mutual distance at least partially under the surface of theliquid, each provided with a closed upper side directed toward theliquid surface, closed side walls and an open underside directed towardthe bottom for enclosing a gas under the liquid surface, wherein the gasis bounded to the underside of the container by a quantity of liquidentering via this underside, which quantity of liquid varies as a resultof the swell,

a transport conduit for transporting gas from the first to the secondcontainer and vice versa, and

generator means responding to the variation in the quantity of liquid inat least one of the containers for generating energy from thisvariation.

In addition to the stated advantages, an installation according to theinvention provides the advantage that when placed at comparatively greatdepth under water it is not very vulnerable, while placing under wateralready provides per se an aesthetic advantage.

The determined first distance between the first and the second containerof an installation according to the invention is in preferencesubstantially equal to half the wave length of the waves occurring inthe swelling liquid.

With such a relation between the said first distance and the wave lengthof the occurring waves the performance with which energy can beextracted from the waves is highest.

The containers are more preferably movable in vertical direction througha determined second distance relative to the bottom by the effect of theupward forces exerted by the swelling liquid.

With such an installation it is possible to generate extra energy fromthe movement of the containers through the determined vertical seconddistance.

In an embodiment of an installation with containers movable in verticaldirection through a determined second distance, this determined distanceis smaller than the difference in height between a ridge and adepression of the waves occurring in the swelling liquid.

It has been found in such an installation that the second distance issufficiently small to cause an up and downward movement of a containerto take place through this distance within a period of one swelling waveat that location.

An embodiment of an installation according to the invention has thefeature that the determined second distance is smaller than thedifference in height between a ridge and a depression of the wavesoccurring in the swelling liquid.

In a preferred embodiment of an installation according to the inventioneach container is coupled for movement in a vertical direction to anupright pillar anchored on the bottom. In such an installation thecontainers are for instance mutually connected via their respectiveupper sides by the transport conduit.

An installation whereof each container is coupled for movement in avertical direction to an upright pillar anchored on or in the bottom andwhereof the containers are mutually connected via their respective uppersides by the transport conduit is characterized in a followingembodiment by a third container similar to the first and secondcontainer and coupled for movement in a vertical direction to a thirdpillar anchored in the bottom, which third container is connected viaits upper side by respective transport conduits to the first and thesecond container via the respective upper sides thereof. Such aninstallation has an exceptionally stable, mechanically strongconstruction.

In another embodiment of an installation according to the invention,wherein each container is coupled for movement in vertical direction toan upright pillar anchored on the bottom, the containers are mutuallyconnected by the transport conduit via their respective undersides.

This latter installation preferably has the feature that a pillardebouches with its upper part into the interior of the container coupledto this pillar.

More preferably the installation has the feature that a pillar deboucheswith its upper part into a tube which is rigidly connected to thecontainer and which extends through and from the upper side of thecontainer vertically outside and inside the container, the top side ofwhich tube is closed and the underside open, and of which the wall ofthe part extending inside the container is provided with apertures,wherein the tube and the pillar have forms such that the pillar fitsinto the tube and the tube is coupled to the pillar for verticalmovement.

In these latter embodiments the transport conduit is for instancecoupled to the respective pillars and mutually connects the containersvia their respective undersides.

Yet another embodiment of an installation wherein each container iscoupled for movement in vertical direction to an upright pillar anchoredon the bottom is characterized by at least one subsequent containersimilar to the first and second container which is coupled for movementin vertical direction to a subsequent pillar anchored on the bottom,which subsequent container is connected by a respective transportconduit to at least the first or the second container.

It is further possible within the scope of the invention to form thewall of a container at least partially of flexible material. A flexiblewall provides particular advantage when the generator means are drivenby a gas which is transported via the transport conduit.

It is further possible within the scope of the invention that acontainer comprises a movable gas-tight partition between a gas forenclosing and an incoming liquid. Such a partition can for instanceconsist of a piston movable in the container or a flexible membraneconnected gas-tightly to the walls. A gas-tight partition has theadvantage that no gas dissolves in the liquid.

Yet another preferred embodiment is characterized in that due to avertical movement of the container this latter also rotates, whereby therotation direction of the container is independent of the verticaldirection of movement. The rotation of the container can take placeround a vertical axis as well as on a horizontal axis. A preferredembodiment of the invention for rotation of the container round avertical axis is characterized in that the container is connected to thepillar anchored on the bottom with interposing of a guide, the guidingdirection of which encloses over at least a part of the length an acuteangle with the direction of the force of gravity. Another preferredembodiment of the invention for rotation of the container round ahorizontal axis is characterized in that the container is connected withinterposing of an arm to a horizontal shaft which is coupled rotatablyto the pillar connected to the bottom. In this preferred embodiment apart of the energy generated during the vertical movement is convertedinto a turning movement of the container. At the dead moments of thevertical movement, i.e. an upper position where an upward movement isconverted into a downward movement and a lower position where a downwardmovement is converted into an upward movement, the container willcontinue to rotate due to the mass inertia thereof. By now extractingenergy from the rotating movement of the container it becomes possibleto extract energy from the intermittent energy source (i.e. the swell)according to a more or less continuous pattern. It is also possible toincrease the stroke length of the vertical movement compared to anon-rotating container.

The invention will now be elucidated further on the basis ofembodiments, while reference is made to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an installation according to a first embodiment with twocontainers connected via their respective upper sides under a flat watersurface,

FIGS. 2-6 show the installation according to FIG. 1 under an undulatingwater surface during different stages of a wave of water travelling overthe installation,

FIG. 7 shows an installation according to a second embodiment with threecoupled containers connected via their respective upper sides,

FIG. 8 shows a wave power plant with a number of installations accordingto FIG. 7,

FIG. 9 shows an installation according to a third embodiment of theinvention with two containers connected via their respective undersides,

FIG. 10 shows an installation according to FIG. 9 under an undulatingwater surface during different stages of a wave of water travelling overthe installation, and

FIGS. 11-15 show installations whereof the containers, in addition tobeing vertically movable, are also rotatable on an axis.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an installation 1 which is placed on the bottom 4 of awater mass 2 with a flat water surface 3. The installation comprises afirst container 5 and a second container 6 respectively coupled topillars 16 and 17 and connected via their otherwise closed upper side 8by a gas transport conduit 15. Containers 5 and 6 comprise closed sidewalls 7 and open undersides 9 respectively 10, via which quantities ofliquid 11, 12 respectively have entered the first and second containers5, 6 respectively. The quantities of liquid enclose a quantity of gas 13and 14 respectively in the first container 5 and second container 6.Containers 5 and 6 are coupled for movement in vertical direction withguides 18 to the respective pillars 16 and 17 such that hydrauliccylinders 19 are driven with the movement of containers 5, 6. Pillars16, 17 are joined on their underside by a connecting arm 20.

When now, as shown in FIG. 2, due to the occurrence of waves thedistance h₁ from the liquid surface 3 to the level of the water mass 11which has penetrated into the first container 5 is greater than thedistance h₂ from the liquid surface 3 to the level of the water mass 12which has penetrated into the second container 6, due to the resultinghydrostatic pressure difference the pressure on the gas 13 in the firstcontainer 5 will rise relative to the pressure on the gas 14 in thesecond container 6, as a result of which gas will be transported in thedirection of the arrows via the transport conduit 15 from the firstcontainer 5 to the second container 6, wherein water enters container 5via the underside 9 and water flows out of container 6 via underside 10.Due to the resulting weight increase of the first container 5 and theweight decrease of the second container 6 the first container 5 willwant to sink, while the second container 6 will tend to start floating.The first container 5 will start a downward movement, guided hereinalong pillar 16 by guides 18, while the second container 6 starts anupward movement, guided herein along the second pillar 17 by runners 18.During the respective downward and upward movement of the first 5 andthe second container 6 energy is generated using the hydraulic cylinders19 driven by the respective containers 5, 6.

FIG. 3 shows the first container 5 and the second container 6 in theirlowest respectively highest position at a moment when the firstcontainer 5 is situated precisely beneath the ridge and the secondcontainer 6 precisely beneath the depression of a wave and the heightsh₁, and h₂, of the columns of water above the liquid levels of the watermasses 11 and 12 in the respective containers 5 and 6 are preciselyequal, so that the transport of gas from the first container 5 to thesecond container 6 and the transport of liquid in and out of therespective containers 5 and 6 has come to a standstill. FIG. 3 furthershows that the horizontal distance between the first container 5 and thesecond container 6 is equal to half the wave length of the wavesoccurring in the swelling water mass. The height of containers 5 and 6is chosen such that this is greater than the maximum occurringdifference in level of the incoming quantity of water, so that undernormal conditions (for instance excluding very violent storm) no wateris transported via transport conduit 15 from the first container 5 tothe second container 6 and vice versa.

FIG. 4 shows the situation wherein the wave ridge of FIG. 3 hasdisplaced further to the left, as a result of which the mean height ofwater column h₂ above the quantity of liquid 12 in the second container6 is more than the mean height h₁ of the water column above the watermass 11 in the first container 5, as a result of which the pressure onthe gas 14 in the second container 6 is higher than the pressure on thegas 13 the first container 5, so that gas transport via transportconduit 15 will take place in the direction designated by the arrows andwater enters container 6 via opening 10 and water is pressed outside viathe opening 9 of the first container 5.

FIG. 5 shows that as a result of this water transport the weight of thefirst container 5 with contents 11 decreases and the weight of thesecond container 6 with contents 12 increases, whereafter the firstcontainer 5 becomes subjected to an upward pressure and the secondcontainer 6 becomes subjected to a downward pressure, as indicated bythe vertical arrows along the respective pillars 16 and 17.

FIG. 6 shows the first container 5, from which practically all the water11 has disappeared, in its highest position, and the second container 6,which is filled practically wholly with water 12, in its lowestposition, while the mean height of water columns h₁ and h₂ above thequantities of liquid 11 and 12 in the respective containers 5 and 6 isthe same, so that transport of gas no longer takes place from the secondcontainer 6 to the first container 5 via conduit 15 and the entry andexit of water respectively into the second container 6 and out of thefirst container 5 have ceased. The first container 5 is then situatedprecisely beneath a wave depression and the second container 6 issituated precisely beneath a wave ridge. As the wave above containers 5,6 displaces further, the pressure on the gas 13 in the first container 5will once again increase and the pressure on the gas 14 in the secondcontainer 6 will again decrease, as a result of which the gas is againtransported from the first container 5 to the second container 6, waterenters the first container 5 and water flows outside from the secondcontainer 6, as a result of which the first container 5 is again guideddownward along the first pillar 16 and the second container 6 againmoves upward along the second pillar 17 while energizing the hydrauliccylinders 19 with which energy is generated.

FIG. 7 shows an installation 21 with three coupled containers of thetype shown in FIGS. 1-6. Containers 22 are coupled via their respectiveupper sides by gas transport conduits 23 which are each provided with aventing valve 25 and with a balloon valve 25. With these latter thecontainers can be closed separately in the case the installation has tobe brought to the surface, for instance for maintenance or repairoperations. Containers 22 are coupled using guides 26 and runners 18 toupright pillars 27 for a movement in vertical direction along thesepillars 27. During the movement of a container 22 in vertical directiona hydraulic cylinder 19 is again energized, whereby energy is generated.Pillars 27 are connected on their underside to tunnels 28 which runtogether in a control chamber 30, the interior of which can be reachedvia an access door 31. Incorporated in the tunnels 28 is for instance anair feed 29 so that in the case of an air shortage in containers 22 thisshortage can be supplemented. A shortage can for instance occur becauseduring violent storm too much water penetrates into the containers 22 orbecause in the course of time air from the containers 22 dissolves inthe sea-water. Control chamber 30 comprises for instance a hydrauliccontrol for hydraulic cylinders 19, a hydro-electric transformer forgenerating energy and control and measuring equipment.

FIG. 8 shows a wave power plant which comprises a number of electricallycoupled installations 21 of the type shown in FIG. 7. The energygenerated by the installations 21 is carried to an onshore coast station35 via cables 32, the junction 33 located in the sea and a main cable34. By positioning the installations 21 such that the wave ridges arrivesuccessively at the location of these installations 21, it is possibleto create a practically constant supply of energy.

FIG. 9 shows an installation 36 according to a third embodiment of theinvention with two containers 37, 38 coupled via their respectiveundersides 9, 10. Containers 37, 38 comprise closed side walls 39, anopen underside 9 respectively 10 and a closed upper wall 40, to which isconnected a tube 41 which extends through and from this upper side 40vertically outside and inside the respective containers 37, 38. Tube 41is in each case closed at its top 46 and is provided in the partextending in the respective containers 37, 38 with apertures 42. Thefirst container 37 is movable in vertical direction along a firstupright pillar 44 using guides 43 and the second container 38 islikewise movable along a second upright pillar 45 via guides 43. Theupright pillars 44, 45 are open at their top and debauch into the tube41 of the first container 37 respectively the second container 38 andare connected on their underside by a gas transport conduit 15. Therespective tubes 41 are coupled with their respective tops 46 via adrive rod 47 to the piston 48 of a hydraulic cylinder 19 anchored to thesea-bed, using which energy is generated from the up and downwardmovement of the first 37 and second container 38 and the tubes 41coupled thereto under the influence of occurring waves. The figurefurther shows internal guides 49 connected to the drive rods 47. Notshown in FIG. 9 are closing devices for closing the apertures 42 inorder to prevent water entering the gas transport conduit 15. Such aclosing device comprises for instance a vertically movable slideprovided with a flexible material, for instance rubber, which is pressedby the water in a container onto the aperture 42 in tube 41, whereby thetube is closed. Such a slide is activated for instance during a stormwhen the occurring waves become so high that there is a danger of theinstallation 36 being wholly filled with water.

FIGS. 10a-j show successive stages of the operation of the installation36 of FIG. 9 under the influence of a wave of water progressing in thedirection of the arrow (to the right in the figure).

Under the influence of the hydrostatic pressure caused by a wave ridgethe first container 37 in figure a is practically wholly filled withwater and the second container 38 is practically wholly empty. As aresult the first container 37 sinks and the second container 38 rises asshown in figure b. Because the wave ridge above the first container 37has disappeared and a wave ridge begins to occur above the secondcontainer 38, the pressure on the gas 13 in the first container 37decreases and the pressure on the gas 14 in the second container 38rises, as a result of which gas is transported via conduit 15 from thesecond container 38 to the first container 37, while water 12simultaneously flows into the second container 38 and water 11 flows outof the first container 37, as shown in figure c. A second wave ridgemeanwhile approaches the first container 37, as a result of which thehydrostatic pressure exerted on the gas 13 in this container 37increases, as a result of which gas is again transported via conduit 15from the first container 37 to the second container 38 with simultaneousentry of water 11 into the first container 37 and exit of water 12 fromthe second container 38 as shown in figure d. Figure e shows thesituation after the second wave ridge has passed over the firstcontainer 37 and therefore corresponds wholly with figure a. Themovement of the first 37 and the second container 38 under the influenceof the waves 3 as according to the successive figures f-j is therefore arepetition of the movement of the figures b-e and so on.

Like the embodiment of FIG. 1, the installation according to FIG. 9 canalso be coupled to more than one similar installation using gastransport conduits 15. In the depicted embodiments energy is alwaysextracted from the system using mechanically coupled hydraulic cylinders19. It is however also possible to generate energy using turbines whichare placed in the transport conduits 15 and driven by the gas flowsthrough conduits 15.

Not shown in the figure are control means and blocking means forblocking the movement of the containers subject to the upward forcesexerted on the containers by the liquid. Such control and blocking meanshave the advantage that it is hereby possible to permit the verticalmovement of the containers only at the moment maximum filling isreached, so that the forces exerted on the containers are maximal andthe energy to be generated from the movement of the containers is thusalso maximal. These control means comprise for instance a force sensorfor measuring the upward force on a container, or a liquid sensor formeasuring the liquid level in a container.

Also not shown are pumping means for draining liquid out of theinstallation, in particular out of the transport conduit 15. Such apump, and also the compressor for the air supply line 29 shown in FIG.7, can be driven in exceptionally efficient manner using a verticallymovable buoy connected to the installation. The pump and the compressorcan of course also be driven using a diesel motor or an electric motorrunning on a battery powered by a solar collector.

FIG. 11 shows a number of installations 50 mutually connected by gastransport conduits 51. The installations 50 each comprise a plurality ofseparate container segments 52. For a further description reference ismade to FIG. 12 in which a detail of FIG. 11 is shown. The containersegments 52 are connected, with interposing of arms 53, to horizontalrotation shafts 54. A vertical movement of container segments 52 is onlypossible when the arms 53 swivel round the rotation shafts 54. In thismanner there results a rotation of container segments 52 roundhorizontal rotation shafts 54. A discharge and feed 55 for gas isconnected to the gas conduit 51 with interposing of a flexible tube part56.

FIG. 13 shows an installation 57 in which generators 59 fixedlyconnected to a container 58 engage with interposing of runners 60 ontoguide tracks 61 rigidly connected to a pillar 62. It is conceivable forthe guide tracks 61 to have a position adjustable in relation to pillar62. By varying the angle between the guide tracks 61 and pillar 62 it ispossible to adapt the installation 57 to different wave heights. It isof course also possible to embody a similar installation with only oneguide track 61 or more than the two guide tracks 61 shown here.

FIG. 14 shows in detail the edge of the container 58, wherein threegenerators 63 with associated runners 64 are arranged. The runners 64co-act with a guide 65. For good operation the runners 64 must have somefreedom of movement relative to container 58 and for this purpose thegenerators 63 are accommodated in a housing 66 which provides thisfreedom.

Shown schematically in FIG. 15 is an installation 67 wherein generators69 rigidly connected to a pillar 68 engage with interposing of runners70 onto a guide track 71 which is recessed as groove 72 in the innerwall of a container 73. Up to certain point this installation is thusthe reverse of the installation 57 shown in FIG. 13. In FIG. 15 thegenerators 69 are rigidly disposed relative to a guide track 71 notrigidly connected to the pillar 68, while in FIG. 13 guide tracks 61connected rigidly to the pillar 62 co-act with generators 59 not rigidlyconnected to pillar 62.

We claim:
 1. An installation for extracting energy from a liquid inwhich swell occurs relative to a bottom, comprising:a first container,and second container spaced from each other at a substantiallyhorizontal first mutual distance with the containers at least partiallyunder a surface of the liquid, with each container provided with aclosed upper side directed toward the liquid surface, closed side wallsand an open underside directed toward the bottom, with the containersconfigured to enclose a gas under the liquid surface, wherein the gas isbounded on the underside of the container by a quantity of liquidentering via the underside of the container which quantity of liquidvaries as a result of the swell; a transport conduit extending betweenthe containers for transporting gas between the first container and thesecond container; and generator means responding to the variation in thequantity of liquid in at least one of the containers for generatingenergy from this variation, wherein both the first and second containersare movable in a vertical direction through a second distance relativeto the bottom by upward forces exerted by the swelling liquid.
 2. Theinstallation as claimed in claim 1, wherein the first distance issubstantially equal to half the wave length of waves occurring in theswelling liquid.
 3. The installation as claimed in claim 1, wherein thesecond distance is less than a difference in height as measured from thebottom between a ridge and a depression of waves occurring in theswelling liquid.
 4. The installation as claimed in claim 1, wherein thesecond distance is greater than the vertical distance between the upperside and the underside of the container.
 5. The installation as claimedin claim 1, wherein each container is coupled for movement in thevertical direction to an upright pillar anchored on the bottom.
 6. Theinstallation as claimed in claim 5, wherein the transport conduitmutually connects the first and second containers via their respectiveupper sides.
 7. The installation as claimed in claim 6, including athird container having an upper side and coupled for movement in thevertical direction to a third pillar anchored on the bottom, which thirdcontainer is connected via its upper side by transport conduits to thefirst container and the second container.
 8. The installation as claimedin claim 6, wherein the transport conduit mutually connects thecontainers via their respective undersides.
 9. The installation asclaimed in claim 5, wherein each pillar has an upper part whichdebouches into an interior of the container coupled to the pillar. 10.The installation as claimed in claim 9, wherein the transport conduit iscoupled to the respective pillars and mutually connects the containersvia their respective undersides.
 11. The installation as claimed inclaim 10, including at least one subsequent container coupled formovement in the vertical direction to a subsequent pillar anchored inthe bottom, which subsequent container is connected by a transportconduit to at least one of the first and the second containers.
 12. Theinstallation as claimed in claim 1, wherein the generator means aredriven by gas which is transported via the transport conduit under theinfluence of the variation of the quantity of liquid in at least onecontainer.
 13. The installation as claimed in claim 1, wherein at leastone of the containers is mechanically coupled to the generator means.14. The installation as claimed in claim 1, wherein the generator meanscomprise hydraulic cylinders.
 15. The installation as claimed in claim1, including control means and blocking means for blocking the movementof the containers subject to the upward forces exerted on the containersby the liquid.
 16. The installation as claimed in claim 15, wherein thecontrol means comprise a force sensor.
 17. The installation as claimedin claim 1, including pumping means for draining liquid out of theinstallation.
 18. The installation as claimed in claim 17, including avertically movable buoy coupled to the installation for driving thepumping means.
 19. The installation as claimed in claim 1, including gassupply means for feeding gas to the installation.
 20. The installationas claimed in claim 19, including a vertically movable buoy coupled tothe installation for driving the gas supply means.
 21. The installationas claimed in claim 1, wherein a portion of at least one of thecontainers is formed at least partially of flexible material.
 22. Theinstallation as claimed in claim 1, wherein at least one containercomprises a movable gas-tight partition between the gas and an incomingquantity of liquid.
 23. An installation for extracting energy from aliquid in which swell occurs relative to a bottom comprising:a firstcontainer and second container spaced from each other at a substantiallyhorizontal first mutual distance with the containers at least partiallyunder a surface of the liquid, with each container provided with aclosed upper side directed toward the liquid surface, closed side wallsand an open underside directed toward the bottom, with the containersconfigured to enclose a gas under the liquid surface, wherein the gas isbounded on the underside of the container by a quantity of liquidentering via the underside of the container which quantity of liquidvaries as a result of the swell; a transport conduit extending betweenthe containers for transporting gas between the first container and thesecond container; and generator means responding to the variation in thequantity of liquid in at least one of the containers for generatingenergy from this variation, wherein the containers are movable in avertical direction through a second distance relative to the bottom byupward forces exerted by the swelling liquid, wherein each container iscoupled for movement in the vertical direction to an upright pillaranchored on the bottom, wherein each pillar has an upper part whichdebouches into a tube which is rigidly connected to the containercoupled to the pillar and which extends through and from the upper sideof the container vertically outside and inside the container, a top sideof which tube is closed and an underside is open, and of which a wall ofthe part of the tube extending inside the container is provided withapertures, wherein the tube and the pillar are configured such that thepillar fits into the tube and the tube is coupled to the pillar forvertical movement.
 24. The installation as claimed in claim 23,including a closing device for closing the apertures in the wall of thetube.
 25. An installation for extracting energy from a liquid in whichswell occurs relative to a bottom, comprising:a first container and asecond container spaced from each other at a substantially horizontalfirst mutual distance with the containers at least partially under asurface of the liquid, with each container provided with a closed upperside directed toward the liquid surface, closed side walls and an openunderside directed toward the bottom, with the containers configured toenclose a gas under the liquid surface, wherein the gas is bounded onthe underside of the container by a quantity of liquid entering theunderside of the container, which quantity of liquid varies as a resultof swell; a transport conduit extending between the containers fortransporting gas between the first container and the second container;and generator means responding to the variation in the quantity ofliquid in at least one of the containers for generating energy from thisvariation, wherein due to a vertical movement of the container, thecontainer rotates, with a rotation direction of the container beingindependent of the vertical direction of movement.
 26. The installationas claimed in claim 25, wherein the container rotates round a verticalaxis.
 27. The installation as claimed in claim 25, wherein the containeris connected to a pillar anchored on the bottom with interposing of aguide, a guiding direction of which encloses over at least a part of itslength an acute angle with the direction of the force of gravity. 28.The installation as claimed in claim 25, wherein the container rotatesround a horizontally situated axis.
 29. The installation as claimed inclaim 28, wherein the container is connected with interposing of an armto a horizontal shaft which is coupled rotatably to a pillar connectedto the bottom.